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J. Exp. Med.,
Volume 187, Number 4, February 16, 1998 655-660
By

From the * Theodor-Kocher Institute, University of Bern, CH-3000 Bern 9, Switzerland, and the Although most leukocytes, T lymphocytes in particular, respond to several different chemokines, there is virtually no information on chemokine activities and chemokine receptors in B
lymphocytes. A putative chemokine receptor, BLR1, that is expressed in Burkitt's lymphoma
cells and B lymphocytes was cloned a few years ago. Deletion of the gene for BLR1 yielded
mice with abnormal primary follicles and germinal centers of the spleen and Peyer's patches,
reflecting the inability of B lymphocytes to migrate into B cell areas. By screening expressed sequence tag DNA sequences, we have identified a CXC chemokine, termed B cell-attracting
chemokine 1 (BCA-1), that is chemotactic for human B lymphocytes. BCA-1 cDNA encodes a protein of 109 amino acids with a leader sequence of 22 residues. The mature protein shares
23-34% identical amino acids with known CXC chemokines and is constitutively expressed in
secondary lymphoid organs. BCA-1 was chemically synthesized and tested for activity on murine pre-B cells 300-19 transfected with BLR1 and on human blood B lymphocytes. In transfected cells, BCA-1 induced chemotaxis and Ca2+ mobilization demonstrating that it acts via
BLR1. Under the same conditions, no activity was obtained with 10 CXC and 19 CC
chemokines, lymphotactin, neurotactin/fractalkine and several other peptide ligands. BCA-1
was also a highly effective attractant for human blood B lymphocytes (which express BLR1),
but was inactive on freshly isolated or IL-2-stimulated T lymphocytes, monocytes, and neutrophils. In agreement with the nomenclature rules for chemokine receptors, we propose the term
CXCR5 for BLR1. Together with the observed disturbance of B cell colonization in BLR1/ CXCR5-deficient mice, the present results indicate that chemotactic recruitment by locally
produced BCA-1 is important for the development of B cell areas of secondary lymphoid tissues.
Biomedical Research Center, University of British Columbia, Vancouver, BC V6T 1Z3 Canada
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